Design, synthesis and photovoltaic properties of two π-bridged cyclopentadithiophene-based polymers

Double acceptor donor–acceptor alternating conjugated polymers containing cyclopentadithiophene, benzothiadiazole and thienopyrroledione: toward subtractive color organic photovoltaics

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] To tune the optical and electrical properties of the available active materials, new chemical motifs incorporating fused rings and alternating donor-acceptor (D-A) structures in the polymer chain have been designed and synthesized. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Benzothiadiazole (BT) and its analogs have been used as electron acceptor groups in conjunction with various donor units such as cyclopentadithiophene (CPDT); compounds containing these acceptor groups exhibit lower-energy levels and a reduction in the band gap compared with other D-A alternating copolymers. [23][24][25][26][27][28][29] Since the development of poly [4,4- Figure 1), one of the first efficient third-generation donor-type conjugated polymers, …”

Polymer design for solar cell – Current trend and future scenario

“…However, addition of DIO reduces the V oc [39,40]. In most of the high performance low band gap (LBG) polymer systems reported so far, adding a certain amount of DIO, 1-chloronaphthalene (CN) or 1,8-octanedithiol (ODT) can facilitate the formation of nanoscale phase separation of polymer:PCBM blend during spin-coating and thus greatly enhances the PCE [41] (see Fig. 2).…”

“…Further, incorporation of p-bridge like 4-hexylthiophene into the polymer was made to facilitate easy processibility and improved property of the resulting polymer. The two polymers with and without the fluorination having a p-bridge between the donor and the acceptor (P120, P121) were synthesised by Yang et al The polymer P121 having fluorination and p-bridge showed an improved solubility and easy processibility when compared to its nonfluorinated analogue and has a PCE of 5.85% and V oc of 0.7 V [41]. The D-A polymer of CPDT with another very good electron withdrawing group, isoindigo was investigated with a diimide group on it.…”

Dithieno[3,2-b:2′,3′-d]silole-based low band gap polymers: the effect of fluorine and side chain substituents on photovoltaic performance

“…However, the solubility has been reduced 18,20,21 due to the enhanced F-H, F-F interactions and strong stacking 23 of polymers, especially for the PCPDTDFBT, the PCE decreased to 3.37% 21 . The 4hexylthiophene had been introduced to PCPDTDFBT as πbridge to improve the solubility in our previous work, and the PCE increased from 3.37% to 5.85% 24 [25][26][27][28] , their results showed that the silicon atom fusion enhances solidstate ordering compared to the carbon-fused analogue, resulting in improved charge transport, which is favorable to get a higher J SC 29 . Y. Yang indicated that the long Si-C bonds displaced the solubilizing side chains further from the thiophene rings, allowing a stronger π-stacking interaction to occur, was the possible reason for the improved charge transport 28 .…”